The line numbers have been changing each year. For 2018 returns, check 1040 line 8 for Standard Deduction or Itemized.
If you have one of these amounts on line 8 you took the Standard Deduction and your state refund is not taxable.
For 2018 the standard deduction amounts are:
Single 12,000 + 1,600 for 65 and over
HOH 18,000 + 1,600 for 65 and over
Joint 24,000 + 1,300 for each 65 and over
Married filing Separate 12,000 + 1,300 for 65 and over
